Many industrial processes generate waste gases comprising carbon dioxide, CO2. Such waste gases may also contain further contaminants that need to be removed before the waste gas can be allowed to be released to the atmosphere, or can be re-used or sent for sequestration of the carbon dioxide. An example of an industrial process that generates waste gases comprising carbon dioxides, and also other contaminants, is the process for producing hydrocarbon products from a gas obtained by coal gasification, such process being known as, for example, the Fischer-Tropsch process, as disclosed in U.S. Pat. No. 1,746,464. Sometimes this and similar processes are referred to as “syngas” processes since they produce synthetic gases from a fuel, such as coal. Purifying and disposing of the waste gases generated in conjunction with syngas processes, and other industrial processes, is difficult and costly, which means that industrial plants operating such industrial processes often generates environmental and health problems.